Surface Field Effect Device Studies for High Resistivity Gallium Arsenide. Part II: Surface Field Effect Transistor

摘要

The use of copper as a means of compensating low resistivity n-type material to high resistivity n-type material was studied. It was found that the optimum diffusion tempera ture for compensation can be predicted by a series of diffusions. A different method for measuring the resistivity of highly compensated semiconductors is described. In this method the semiconductor is made the dielectric of a parallel plate capacitor whose effective parallel resistance and capacitance are measured in a high frequency bridge. Surface field effect transistors using high resistivity n-type single crystal GaAs as the semiconductor are discussed. These transistors consist of two ohmic source and drain contacts of alloyed thin films of indium and nickel, a gate insulator of evaporated SiO and a gate of Al. Transistor characteristics are shown with transconductances as high as 250 micromhos; however, voltage amplification factors are low, typically 0.2 with 6 v on the drain. These characteristics resemble more nearly triodes than pentodes. This limited performance was traced to a low effective surface mobility. (Author)